Most common cause of congenital sensineuronal hearing loss ?
**Core Concept**
Congenital sensorineural hearing loss refers to a type of hearing impairment that is present at birth, affecting the inner ear or the auditory nerve. This condition can be caused by genetic mutations, infections, or environmental factors during fetal development.
**Why the Correct Answer is Right**
The most common cause of congenital sensorineural hearing loss is related to genetic mutations affecting the genes responsible for the development and function of the inner ear. Specifically, mutations in the GJB2 gene, which codes for the connexin 26 protein, are a leading cause of congenital hearing loss. This protein plays a crucial role in the formation of the cochlear membrane and the maintenance of the ion balance in the inner ear. Mutations in GJB2 can disrupt the normal functioning of the inner ear, leading to sensorineural hearing loss.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because while maternal infections such as rubella can cause congenital hearing loss, they are not the most common cause.
**Option B:** This option is incorrect because environmental factors such as exposure to ototoxic substances during pregnancy are not a leading cause of congenital sensorineural hearing loss.
**Option C:** This option is incorrect because while certain genetic syndromes can increase the risk of congenital hearing loss, they are not the most common cause.
**Clinical Pearl / High-Yield Fact**
The GJB2 gene mutation is a common cause of congenital hearing loss, and screening for this mutation is recommended for all newborns with hearing loss.
**Correct Answer:** C. GJB2 gene mutation